MEDROL ACETATE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MEDROL ACETATE (MEDROL ACETATE).

How it works

Methylprednisolone acetate is a corticosteroid that binds to the glucocorticoid receptor, leading to modulation of gene expression and suppression of inflammatory mediators including prostaglandins, leukotrienes, and cytokines.

What the body does with it

Metabolism	Hepatic metabolism primarily via CYP3A4 to inactive metabolites.
Excretion	Primarily renal (urinary) as inactive metabolites. Approximately 10-20% of the dose is excreted unchanged in urine. Biliary/fecal excretion accounts for <5% of the dose.
Half-life	Terminal elimination half-life of methylprednisolone (active form) is approximately 1.8–3.5 hours. The biological half-life (duration of HPA suppression) is longer: 18–36 hours. Clinical context: Short plasma half-life but prolonged tissue effects due to receptor binding.
Protein binding	Approximately 70–90% bound to cortisol-binding globulin (CBG) and albumin. Binding is saturable; at high doses, free fraction increases.
Volume of Distribution	0.5–1.0 L/kg (methylprednisolone). Indicates extensive tissue penetration and distribution into extravascular spaces.
Bioavailability	Oral: 70–80% (methylprednisolone base). IM (methylprednisolone acetate): 80–100% (slow absorption from depot). For Medrol Acetate specifically, oral bioavailability is approximately 80%.
Onset of Action	IM injection: 24–48 hours (for crystalline suspension; slower absorption due to depot effect). Oral (tablets): 1–2 hours.
Duration of Action	IM depot: 1–2 weeks (single dose effect). Oral: Duration of anti-inflammatory effect 12–36 hours after a single dose, correlating with HPA suppression lasting 18–36 hours.

Classification & Brands

Dosing & administration

4 to 48 mg orally once daily or in divided doses (e.g., 4 mg every 6 hours) depending on condition, typically starting at 4-48 mg/day. Also intramuscular (IM) as methylprednisolone acetate: 40-120 mg every 1-4 weeks. Intra-articular or soft tissue: 4-40 mg per injection depending on joint size.

Dosage form	OINTMENT
Renal impairment	No specific dose adjustment required for renal impairment. Hemodialysis not expected to remove drug significantly.
Liver impairment	Child-Pugh A and B: No adjustment needed. Child-Pugh C: Manufacturer data insufficient; consider dose reduction due to potential decreased clearance.
Pediatric use	Oral: 0.05 to 2 mg/kg/day divided every 6-12 hours. IM: 0.03-0.2 mg/kg/day every 1-4 weeks. Intra-articular: 4-10 mg for small joints, 10-40 mg for large joints. Maximum oral: 60 mg/day.
Geriatric use	Initiate at lower end of adult dose (e.g., 4 mg daily). Monitor for hyperglycemia, osteoporosis, and cardiovascular effects. Use lowest effective dose for shortest duration.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MEDROL ACETATE (MEDROL ACETATE).

Breastfeeding	Enters breast milk; M/P ratio approximately 0.4-0.7. Use caution, especially with high doses; monitor infant for growth and adrenal suppression.
Teratogenic Risk	Pregnancy Category C. First trimester: Increased risk of oral clefts (odds ratio 1.3-3.4). Second/third trimesters: Fetal adrenal suppression, intrauterine growth restriction, and oligohydramnios with prolonged use.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

No FDA boxed warning for methylprednisolone acetate.

Side Effect Profile

Common Effects	Thinning of skin Increased risk of infection Reduction in bone density Weight gain Mood changes Upset stomach Behavioral changes
Serious Effects

Absolute Contraindications

["Hypersensitivity to methylprednisolone or any component","Systemic fungal infections","Intrathecal administration","Live or live attenuated vaccines (relative)"]

Clinical Precautions

Precautions

["Immunosuppression and increased risk of infections","Adrenal suppression with prolonged use or abrupt withdrawal","Osteoporosis with long-term use","Gastrointestinal perforation or bleeding","Cushing's syndrome with chronic therapy","Exacerbation of underlying infections or masking of signs","Thrombotic events","Avascular necrosis of femoral head","Anaphylaxis/hypersensitivity reactions","Growth suppression in children"]

Clinical Tips & Counseling

Drug interactions

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MEDROL ACETATE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MEDROL ACETATE (MEDROL ACETATE).

How it works

What the body does with it

Metabolism	Hepatic metabolism primarily via CYP3A4 to inactive metabolites.
Excretion	Primarily renal (urinary) as inactive metabolites. Approximately 10-20% of the dose is excreted unchanged in urine. Biliary/fecal excretion accounts for <5% of the dose.
Half-life	Terminal elimination half-life of methylprednisolone (active form) is approximately 1.8–3.5 hours. The biological half-life (duration of HPA suppression) is longer: 18–36 hours. Clinical context: Short plasma half-life but prolonged tissue effects due to receptor binding.
Protein binding	Approximately 70–90% bound to cortisol-binding globulin (CBG) and albumin. Binding is saturable; at high doses, free fraction increases.
Volume of Distribution	0.5–1.0 L/kg (methylprednisolone). Indicates extensive tissue penetration and distribution into extravascular spaces.
Bioavailability	Oral: 70–80% (methylprednisolone base). IM (methylprednisolone acetate): 80–100% (slow absorption from depot). For Medrol Acetate specifically, oral bioavailability is approximately 80%.
Onset of Action	IM injection: 24–48 hours (for crystalline suspension; slower absorption due to depot effect). Oral (tablets): 1–2 hours.
Duration of Action	IM depot: 1–2 weeks (single dose effect). Oral: Duration of anti-inflammatory effect 12–36 hours after a single dose, correlating with HPA suppression lasting 18–36 hours.

Classification & Brands

Dosing & administration

Dosage form	OINTMENT
Renal impairment	No specific dose adjustment required for renal impairment. Hemodialysis not expected to remove drug significantly.
Liver impairment	Child-Pugh A and B: No adjustment needed. Child-Pugh C: Manufacturer data insufficient; consider dose reduction due to potential decreased clearance.
Pediatric use	Oral: 0.05 to 2 mg/kg/day divided every 6-12 hours. IM: 0.03-0.2 mg/kg/day every 1-4 weeks. Intra-articular: 4-10 mg for small joints, 10-40 mg for large joints. Maximum oral: 60 mg/day.
Geriatric use	Initiate at lower end of adult dose (e.g., 4 mg daily). Monitor for hyperglycemia, osteoporosis, and cardiovascular effects. Use lowest effective dose for shortest duration.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MEDROL ACETATE (MEDROL ACETATE).

Breastfeeding	Enters breast milk; M/P ratio approximately 0.4-0.7. Use caution, especially with high doses; monitor infant for growth and adrenal suppression.
Teratogenic Risk	Pregnancy Category C. First trimester: Increased risk of oral clefts (odds ratio 1.3-3.4). Second/third trimesters: Fetal adrenal suppression, intrauterine growth restriction, and oligohydramnios with prolonged use.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

No FDA boxed warning for methylprednisolone acetate.

Side Effect Profile

Common Effects	Thinning of skin Increased risk of infection Reduction in bone density Weight gain Mood changes Upset stomach Behavioral changes
Serious Effects

Absolute Contraindications

["Hypersensitivity to methylprednisolone or any component","Systemic fungal infections","Intrathecal administration","Live or live attenuated vaccines (relative)"]